Vacuum bag sealing machine



Oct. 23, 1962 R. s. RANDALL VACUUM BAG SEALING MACHINE 3 Sheets-Sheet 1 Filed Dec. 3, 1957 INVENTOR. Qa/ph 5.1?anda/l Oct. 23, 1962 R. s. RANDALL VACUUM BAG SEALING MACHINE 5 Sheets-Sheet 2 Filed Dec. 3, 1957 Oct. 23, 1962 R. s. RANDALL VACUUM BAG SEALING MACHINE 3 Sheets-Sheet 5 Filed Dec. 5, 1957 3,059,389 Patented Get. 23, 1962 Filed Dec. 3, 1957, Ser. No. 700,415 Claims. (til. 53-89) The present invention relates to improvements in a Vacuum Bag Sealing Machine, and contemplates certain improvements over my machines of similar character described in my co-pending applications, Serial Numbers 486,797, now US. Patent No. 2,833,096, 521,176, now US. Patent No. 2,844,925, 550,921, now US. Patent No. 2,870,591, and 643,684, now US Patent No. 2,991,609.

The machines described in the above applications consist essentially of a horizontal platform adapted to have a number of bags arranged thereon in alined relation, a cover or housing hinged to the platform so as to form a vacuum chamber therewith when lowered upon the platform, means for stretching the open ends of the bags, means for evacuating the chamber to draw the air out of the bags, usually followed by the injection of an inert gas into the bags, and means carried by the housing for heat-sealing the bags thus treated.

In the operation of the machines described, it was necessary for the operator, after the completion of each sealing operation, to manually remove the sealed bags and to reload the platform while the machine was standing idle at the cost of considerable time, the loading operation taking about as long as the sealing operation.

In the present invention, which is directed principally to the feeding means of a machine of the character described, means are provided which allow the operator to arrange a new load outside the machine while the latter performs the sealing operation with its attending features.

For this purpose it is proposed to provide an endless belt with an upper stretch of sufficient length to accommodate two sets of bags, with one section of the upper stretch disposed outside the vacuum chamber, or in the sealing zone, while the other section is disposed outside the vacuum chamber to form a loading zone.

The said upper stretch of the belt is made to advance in timed relation to the operation of the machine, so that the operator is free to place a new load on the belt during the sealing operation and the new load automatically advances from the loading zone to the sealing zone when the sealing operation is completed with respect to the previous load.

It is further proposed to provide on the belt successive series of bag-holding trays, each series preferably containing four trays adapted to confine the bags, each tray being made to present an anvil for the open end of the bag against which the sealing operation may be performed, with the belt made sufficiently wide and the series of trays spaced sufficiently to allow the descending cover to form a vacuum chamber therewith.

Again, it is proposed to provide a floating element in the chamber for each tray, the floating element being made to descend with the cover to spread and flatten the main body of each bag after it has entered the sealing zone.

It is additionally proposed to provide means, in connection with the cover, for flattening and anchoring the open end of each bag as the cover descends, this operation being followed by evacuation of the bag and re-filling the same with an inert gas, if desired.

A further object of my invention is to provide certain safety measures to protect the hands of the operator in case the hands should still be in the loading zone when the belt is set in motion for feeding a new load into the sealing zone.

It is also proposed to provide means for conveniently presenting bags to be loaded to the operator, so that the loading operation may be accomplished with a high degree of speed and accuracy.

Further objects and advantages of my invention will be apparent as the specification proceeds, and the new and useful features of my machine will be fully defined in the claims hereto appended.

The preferred form of my invention is illustrated in the accompanying drawings, forming part of this application, in which:

FIGURE 1 shows a side view of my vacuum bag sealing machine;

FiGURE 2, an end view of the same;

FIGURE 3, a plan view of my machine;

FEGURE 4, a detail plan view of one of the trays used in the machine;

FEGURE 5, a section taken along line 55 of FIG- URE 4;

FIGURE 6, a section taken along line 66 of FIG- URE 4-;

FIGURE 7, a section taken along line 77 of FIG- URE l; and FIGURE 8, a sectional detail view taken along line 8-8 of FIGURE 7. i

While I have shown only the preferred form of my invention, it should be understood that various changes or modifications may be made within the scope of the ciairns hereto attached without departing from the spirit of the invention.

Referring to the drawings in detail, my invention comprises, in its principal features, an .endless belt 1 mounted on horizontal rollers 2 and 3 to present an elongated horizontal stretch 4, and a vacuum bag sealing machine 5 adapted for cooperation with the left-hand (FIGURE 1) portion of the belt in forming a sealing zone, a corre sponding right-hand portion of the upper zone being free of access to form a loading zone.

Suitable frame-work 6 is provided for supporting the rollers and the bag sealing machine in such a manner as to bring the upper belt stretch up to a convenient height for loading and sealing operations.

The surface of the belt has a number of series of trays '7 mounted thereon, there being five series shown in the present form, and the series being sufiiciently spaced, as at 8, to allow each series to be conveniently accommodated in the sealing zone. Each series consists of four trays, which again are suitably spaced, as at 9, to provide a desired clearance.

Each tray is intended to accommodate a previously loaded bag and is arranged transversely with respect to the belt, as shown in FIGURE 3. 'Each tray comprises a fiat bottom 10, preferably made of metal, of sufiicient length and width to receive a filled bag thereon, with side flanges 11 for confining the bag. The bottom of the tray is secured upon the belt by means of two rivets 12 (see FIG- URE 6) disposed in the median transverse plane of the tray in such a manner that the trays can follow the c-urva tures of the belt when passing around the supporting rollers (see FiGURE 1). The rivets are countersunk in both the belt and the bottom plate as shown in FIG- URE 6. p

The length of each is such, as compared with the width of the belt, that a portion of the belt projects on each side, as clearly shown in FIGURE 3, the projecting margins of the belt being used to produce a perfect seal about the belt in the sealing zone.

The forward end of the bottom of each tray, toward the operator, extends beyond the flanges 11, as at 13, to ,resent an anvil 14, the latter having a thin strip '15 of sponge neoprene accommodated in a slightly recessed portion of the metal plate and having a second thin strip 16 of solid neoprene superimposed on strip 15.

Just rearwardly of the anvil, I leave a narrow strip 16 which, at one end, is recessed to receive a friction element 17 used in stretching the bag, as will appear later.

The bottom of the tray is covered by layers of sponge neoprene.

It will be noted that the operator, standing forwardly of the right portion of the machine, as seen in FIGURE 1, is confronted with four trays in the loading zone. Rearwardly of the loading zone, that is opposite the operator, I provide -a second belt 18 (see FIGURE 3) one end of which comes about even with the left end of the loading zone, while the other end extends into the factory to suitable places for feeding filled bags upon the same.

Thus, the operator at the loading zone merely has to reach beyond the belt of the machine to the second belt 18 to pull four filled bags from belt 18 upon the four trays of the loading zone, with the open end of each bag presented toward the operator and disposed. over the anvil. The 'belt 18 has a stop 18 to prevent the bags from going beyond the reach of the operator.

The belt 1 is operated for intermittent advance by the motor 19 through gearing 20 and it movement is timed to bring a new series of trays into the sealing zone, after the completion of each sealing operation, while discharging the sealed bags. V

The sealing machine may be constructed substantially along the lines disclosed in the pending application, Ser. No. 643,684, and comprises, in its principal features, a fiat horizontal platform mounted on the frame structure in aplane immediately below the upper belt stretch, the platform being of substantially the same width as the belt and of a length to accommodate one series of trays thereon.

A hollow housing 21 is made to cooperate with the platform 20 in forming a sealing chamber for the loaded belt section. I

- The housing is hinged to the frame structure, as at 22 and is operated for upward and downward swinging movement bymeans of a U-frame 23 fixed with respect to the platform and suitable operating means for the frame, the latter means comprising a brace 24 extending downwardly -from the main frame structure, a cylinder 25 pivoted to the lower end of the brace, as at 26, and having a piston 27 therein, and a connecting rod 28 for the piston having its upper end pivoted to the frame 23, as at 29.

The piston is pressure-operated and is made to swing the housing upward and downward in timed relation to the cycle of operations;

'The platform 20 is formed with an all-around sealing gasket and the housing is provided with a registering gasket 32, the two gaskets being adapted to clamp upon the rimsof the belt and transverse sections thereof as defined by the spaces 8 between the different series of trays, so as'to form a complete seal above the series of trays confined in the sealing zone.

The housing is provided with means for flattening the body portions of the filled bags disposed on the four confined trays, means for anchoring the end edges of the open ends of the bags, means for evacuating the bags, means for refilling the bags with an inert gas, and means for heat-sealing the open ends of the bags, accompanied by the stretching of the open end of each bag just prior to the sealing of the same.

The bag flattening means comprises a curved leaf-spring 33 for each tray having one end secured to the rear wall of the housing, as at 34, and having its other end bearing against the upper wall of the housing, as at 35, with an intermediate downwardly curved section free to flex in response to upward pressure.

A thin plate 36 is riveted to the lower side of the spring intermediate the length thereof, as at 37, this plate being free floating and being of approximately the width of the tray between the flanges thereof. As the housing descends, the plate engages over the upper surface of the bag body and due to its free-floating spring support, tends to flatten out the bag body.

The means for anchoring opposite edges of the open ends of the bag is substantially similar to that described in my application, Ser. No. 643,684, and is illustrated in FiGURES 7 and 8. It comprises a bar 40 extending through the full length of the housing and depending from the upper wall thereof. This bar is fixed and is located to present its lower edge just rearwardly of the strips 16 and the friction element 17 of each tray, when the housing is in closed position.

The bar carries an anchoring means for each tray, and each anchoring means comprises a brace 41 engageable over the right edge of the bag, immediately above the friction element 17, and a roller 42 with rearwardly bent rubber teats 43 engageable over the strip 16 of the tray.

The brace 41 is pivoted to the bar 40, as at 44, and made to lean to the right, as viewed in FIGURE 8, by a stop 45, with a spring 46 urging the brace upon the stop.

The brace has a shoe 17 pivoted to the lower end thereof, this shoe having a fiat bottom adapted to bear on the right edge of the bag end-and to press the same upon the friction element 17 when thehousing is lowered. During this action, the brace is moved slightly away from the stop 45 so that, when pull is exerted on the bag end to the left, the brace is free to swing to the left for tightening the engagement between the shoe and the right edge of the bag end.

As the shoe engages over the right edge of the bag the roller 42 descends upon the left end so as to bring at least one of the iubber teats into gripping engagement with the left edge of the bag end, thereby firmly anchoring the bag, with the extreme end of the bag projecting over the anvil 14. While the end edges of each bag are thus firmly anchored, the intermediate portion of the bag end is still open for passage of air or nitrogen gas therethrough.

Next, vacuum is applied to the chamber through the conduit 50 for evacuating the chamber and the assembled bags, and this operation is followed, in timed relation, by the re-filling of the bags with an inert gas, through the arrangement shown at 51.

This arrangement comprises a pair of tubes 52 depending from the top of the housing and carrying, at their lower ends, an inverted channel 53 extending through the length of the housing slightly forward of the anvils 14. The channel is slidable on the tubes and is urged down wardly by a spring 54, against the belt. The channel is formed with perforations 56 opposite the open ends of the bags and an inert gas is fed into the channel through the tubes 52 and connections shown at 57.

After the bags have been re-filled, the sealing operation takes place; The heat-sealing means comprises a suitably heated bar 60 extending through the length of the chamber. This bar is supported by four rods 61, which in turn are supported by four diaphragms 62 disposed .in four domes 63 rising from the housing in registering relation with the forward ends of the four trays.

. 'I he diaphragms 62 are operated by air pressure to lower the bar 60 when the re-filling operation is completed, and the bar is located directly over the anvil 14 which has the open ends of the bags disposed thereon.

But, before the bar strikes the bags for heat-sealing, it is desirable to smoothen and stretch the open end of the bag, and this operation is performed while the bar descends and before it reaches the bag ends.

This is done by causing the descending bar to impart a turning movement to the roller 42 by means of a slide 63 slidable in a lateral horizontal groove formed in the sealing bar and facing the roller, and a pin 64 projecting from the slide into the roller off center, so that when the sealing bar descends the slide will turn the roller clockwise and will cause the teats of the roller to pull the left band edge of the bag away from the right hand edge and to straighten and tension the open end of the bag before the sealing bar bears down on the same.

During the pulling actiono'n the part of the rubber teats, the shoe 47 tightens its hold on the right end of the bag, because any leftward swing on the brace 41 on its pivot 44 will deepen the engagement.

The diaphragm 62 in each dome divides the latter into upper and lower chambers 64 and 65 and a pressure medium is admitted to the former through conduit 66.

The rubber teats on the roller 44 are preferably made with their outer ends following a circle eccentric with respect to the axis of rotation, so that by proper setting of the teats, the length of pull on the edge of the bag may be adjusted to fit bags of different weights.

A suitable shield 67 may be provided to enclose those parts of the machine not needed for frequent access. At the entrance end of the vacuum sealing machine, I preferably provide a hinged gate 68 which is intended for a safety factor. If the operator should be delayed in filling the trays at the loading zone, and should have his hands still over the trays while the belt begins to move, a slight touch of his fingers or hand against the gate will open a switch 69 in the motor circuit and stop the belt, while a slight upward push on a projecting arm 70 again closes the switch for further operations.

In case the vacuum in the vacuum chamber should tend to lift the belt stretch inside the chamber from the platform 29 of the sealing machine, I provide a plurality of grooves 71 in the top surface of the platform, these grooves being connected to a conduit 72 which again is connected to a source of vacuum, so that a balancing vacuum may be applied to the bottom of the belt stretch.

In operation, the following steps may be distinguished, starting with the position indicated in FIGURE 1, in which the forward portion of the upper belt stretch is located in the sealing zone, while the rearward portion is located in the loading zone.

(1) Assuming that filled bags are fed toward the operator on the secondary belt 8, the operator reaches for the bags and places the same on the four trays 7, making certain that the bags are properly placed, with the sides confined between the flanges 11 and the open ends projecting over the anvils 14, while adjacent neck portions overlie the strips 16 and the friction elements 17.

(2) As the sealing operation for the previous series of bags is completed, the housing swings into open position and the belt moves forwardly sufiiciently to discharge the batch of bags previously sealed and to move the belt stretch just loaded into its proper position within the sealing machine.

(3) Next, the housing is made to descend upon the new belt stretch introduced, either automatically or under manual control, The gaskets 31 and 32 bearing on the top and the bottom of the belt along the edges and transverse portions of the latter now form a complete seal about the loaded trays.

(4) As the housing descends, the floating plates 36 descend upon the filled bags on the trays, flattening and smoothing the body portions and driving out excess air in the process.

(5 At about the same time, or slightly later, the shoes 47 of the braces 41 and the rollers 42 descend upon opposing edges of each bag in the region of the strip 16 and the friction member 17, the shoes clamping the right edges of the bag ends upon the friction members 17, and the lowermost teats of the rollers clamping the left edges of the bag ends upon the strip 16. The two clamps leave the intermediate portion of the bag end open.

(6) Next, evacuation of the chamber and of the bags contained therein is started through the conduit 50.

(7) As the vacuum in the chamber and the bags reaches a desired degree, nitrogen is admitted to the chamber through the tubes 52 and the perforations 56 in the form of jets. These jets, in case the two sheets of the bag are too close to present an opening, will pass over the upper surface of the upper sheet and produce enough suction on the upper sheet to lift the same and open the bag.

6 This feature is very important, since if the nitrogen is fed from any other point, there is a tendency for the nitrogen to close the bag and to keep the nitrogen out of the bag.

-(8) When the desired nitrogen pressure, still less than atmospheric, has been reached, the pressure operates a valve admitting nitrogen or air at atmospheric pressure to the upper side of the diaphragm 62, and the diaphragm pushes the sealing element 60 downward.

(9) The slides 63 of the sealing element, through the pins 64, bear down on the rollers 42, causing the same to turn clockwise and causing the lower teats to exert pull to the left on the left edges of the bags, that is, away from the shoes, thereby tightening the hold of the shoes and smoothing and stretching the open ends of the bags.

(10) The sealing element descends upon the open end of the bags, over the anvil 14, and heat-seals the bags.

(11) After a predetermined time, allowed for the sealing operation, the chamber is vented to thatrhosphere, the cover is raised and a vacuum is applied to the diaphragm 62 to cause the heater bar to return to its initial position.

(12) The belt begins moving, discharging the sealed bags over the roller 2 and drawing in a new charge of trays, which have been loaded by the operator during the sealing operation.

The operation of the belt and the housing is mainly controlled by a switch 75 disposed at the right-hand end of the belt and involving a stationary contact 76 ,and a plurality of conduits 77 mounted on the belt substantially midway in the spaces 8 between the different groups of trays.

With the belt in motion, when one of the contacts 77 reaches the contact 76, the belt movement stops immediately, so as to bring one loaded belt section within the vacuum chamber and to leave the next unloaded belt section outside the vacuum chamber in a predetermined position.

The stopping of the belt is followed immediately by the closing of the housing through the cylinder 25, by any suitable agency well-known in the art and the closing of the housing is accompanied or followed by the various steps resulting in the sealing of the bag.

After the operation is completed, the housing may be lifted by any suitable agency, as by a time switch, not shown, followed by the opening of the switch 75 which allows the belt movement to continue until the next contact 77 reaches the contact 76 for closing the switch.

Instead of using the grooves 71 for applying suction to the upper belt stretch from below, I may provide holes in the belt itself which will immediately balance pressures on opposite faces of the belt.

The rollers 42 may be mounted on the bar 40 with freedom of horizontal adjustability for adjusting the spacing between the rollers and the braces 41 for bags of different widths.

I claim:

1. In a vacuum bag sealing machine, a frame structure having a horizontal platform, an endless belt mounted to present an upper stretch with a forward portion overlying the platform and a rearward portion outside the platform, and a housing descendable upon the platform, the housing and the platform having cooperative means for forming a seal about the forward portion of the belt, and the housing having means for evacuating the space above said belt portion, and the platform having means for applying a vacuum to the bottom of said belt portion to prevent the vacuum above the belt portion from lifting the belt from the platform.

2. In a vacuum bag sealing machine, a pair of horizontally spaced rollers, an endless belt guided about the rollers to present a horizontal upper stretch, and a series of bag-holding trays mounted upon the belt, the trays being mounted on the belt transversely to the length of the belt and having opposing side flanges for confining the bags thereon, andthe side flanges of each tray being made to stop short of the forward end of the tray to leave a front portion of the tray free for sealing operations, the said front portion including'a flat anvil section at the extreme front end and a flat clamping section rearwardly of the anvil section.

3. -In a vacuum bag sealing machine, a horizontal platform, an endless belt having spaced groups of bag-receiving trays thereon and being operable for successively advancing the groups of trays over the platform, a housing descendable on the platform and adapted to confine a group of trays therein, the trays having flat anvil sections at their forward ends and anchoring strips rearwardly of the anvil sections, and the housing having anchoring means disposed to descend on the anchoring strips as the housing descends for clampingly engaging bag portions interposed therebetween and having sealing elements descendable upon the anvil sections for sealing interposed portions of the bags.

4. In a vacuum bag sealing machine, a horizontal platform, an endless belt having spaced groups of bag-receiving trays thereon and being operable for successively advancing the groups of trays over the platform, a housing descendable on the platform and adapted to confine a group of trays therein, the trays having fiat anvil sections at their front ends and anchoring strips rearwardly of the anvil sections, and the housing having anchoring means disposed to descend on the anchoring strips as the housing descends for clampingly engaging bag portions interposed therebetween and having sealing elements descendable upon the anvil sections for sealing interposed 8 sections of the bags, and the sealing elements having means cooperable with the anchoring means for stretching bag portions held by the anchoring means.

5. In a vacuum bag sealing machine, a bag-holding tray comprising a fiat rectangular bottom adapted to receive a bag thereon, and side flanges rising from the edges of the tray to confine the bag, the side flanges stopping short of the front of the plate so as to leave the front portion unobstructed to present an anvil section at the extreme front end and a bag clamping section rearwardly of the anvil section, the anvil section being stepped down and having a thin strip of sponge neoprene and a second strip of solid neoprene superimposed thereon, and the bag clamping section having a friction element mounted thereon for use in stretching operations.

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